21. --- Oh, it’s you! I ________ you.
--- I’ve just had my hair cut and I am wearing new glasses.
A. didn’t recognize B. hadn’t recognize C. haven’t recognize D. don’t recognize
22. One of the engines of the plane was out of order and the bad weather ________ the difficulty.
A. added to B. added up C. added up to D. added
23. You can never imagine what great difficulty I had ________ his parents.
A. to find B. of finding C. finding D. about finding